Sir Elton John and other stars are pricking their fingers and tweeting the images in a campaign to support the fight against Aids and promote compassion for patients.

The images to be tweeted on Valentine's Day by celebrities including Elizabeth Hurley, Stephen Fry, Jamie Oliver and Kelly Osbourne will be accompanied by the words "Love Is In My Blood".

Other stars involved in the campaign, which was devised by Sir Elton's Aids Foundation, include Jessie J, Florence Welch, David Walliams and Lara Stone.

While new HIV infection rates have dropped by up to 50% in many countries over the last two years, the foundation says the prejudices that often accompany the disease also need to be tackled.

Sir Elton said: "Now more than ever we know how to beat Aids.

"Thanks to incredible work by the Aids community over the past 20 years we now have affordable, quality treatment which saves lives and dramatically reduces the chances of passing on HIV.

"But these medicines don't work against prejudice and discrimination. It’s time to stop treating people who are most vulnerable to HIV as outcasts. Everyone deserves the chance to protect themselves. Surely we have enough love for that."

The singer's Aids Foundation marks its 20th anniversary this year.

A short video by artist Ai Weiwei, featuring the words "Love Is In Our Blood" to the sound of a heartbeat, was running on Valentine's Day across screens in Piccadilly Circus, Times Square and Independence Square in Kiev.

"When Elton asked me to create something for the Foundation, I wanted to contribute by finding an expression that raises awareness for this crisis among as many people as possible," Ai said.

David Furnish, the chairman of the Elton John Aids Foundation and the singer's partner, said: "Of course we want people to protect themselves, and everything we fund promotes safe sex, clean disposable needles and condom use.

"What pumps through our veins is also the love and compassion to keep one another safe and look after people when they need it."